1. Field of the Invention (Technical Field)
The present invention relates to the field of sleep prevention, and more particularly to a method and an apparatus for detecting and awakening a person who is becoming drowsy.
2. Background Art
The maintenance of a state of wakefulness while performing various tasks is needed for a range of reasons varying from safety to efficient performance and beyond. In order to decrease the possibility of accidents, alertness while operating vehicles, such as automobiles or heavy machinery, must be maintained. Additionally, reading and studying require wakefulness.
There are several devices described in the prior art which detect drowsiness and awaken the user upon its detection. While many base their determinations on eyelid motion and a predetermined blink frequency, for various reasons they have caused discomfort for the user. For example, several patents require a "feeler" element which maintains contact with the user's eyelid (e.g., U.S. Pat. No. 5,469,143, entitled "Sleep Awakening Device For Driver Of Motor Vehicles," to Cooper). Others shine beams of light either into the user's eye or across the line of vision such as disclosed in U.S. Pat. No. 4,967,186, entitled "Method And Apparatus For Fatigue Detection," to Ludmirsky, et al., and U.S. Pat. No. 4,144,531, entitled "Drowsiness Detecting Apparatus," to Anbergen.
Not all prior art devices determine drowsiness based on eyelid motion; there are several which monitor head inclination. These seem to be particularly designed for operators of vehicles. They are mounted in different ways: On the headrest (U.S. Pat. No. 3,903,514, entitled "Stay Awake Alarm," to Mazzola); in a collar (U.S. Pat. No. 5,488,354, entitled "Snooze Alert Device," to Colvin); or in a cap (U.S. Pat. No. 5,522,092, entitled "Cap With Sleep Posture Alarm," to Streb, et al.). U.S. Pat. No. 4,463,347, entitled "Drowsiness Alarm System For A Vehicle," to Seko, et al., bases its determination on changes in the angle of the steering wheel. Still another, U.S. Pat. No. 5,311,877, entitled "Waking Degree Maintaining Apparatus," to Kishi, teaches correlating brain waves to reaction time.